THE SUPRARENAL SYSTEM 241 



The most reliable results have been obtained by means of 

 intravenous injection (Erb, B. Fischer, K. Ziegler, Lissauer, 

 Braun, Minorescu, Scheidemandel, v. Koranyi, Pearce and Stan- 

 ton, v. Rzentkowski, Kiilbs, Hedinger, Loeb, Loeper, v. Frey 

 and Meyer, Pic and Bonnamour, &c.). Kaiserling is the only 

 author who is not convinced that the changes in the aorta are 

 directly due to the action of adrenalin. The vast majority of 

 authors hold the opinion that the results of adrenalin experiments 

 are in no sense accidental, and that there is, as far as we know 

 at present, no reason to doubt that the changes observed in the 

 vessels of rabbits are the outcome of the action of this substance. 



The vascular changes take place in response to quite small 

 quantities of adrenalin. Braun found that, after a single in- 

 jection of .1 mg., several calcareous foci were present in the 

 aorta ; he found, also, that the repeated injection of .001 mg. of 

 Clin's adrenalin, or even of fractions of this quantity, offered the 

 best means of studying the preliminary stages of "adrenalin 

 sclerosis." 



Speaking broadly, these changes take place more readily in 

 old animals than in young ones ;* there are, moreover, certain 

 idiosyncrasies peculiar to individuals and to varieties, f but there 

 is no sex incidence (Bennecke) ; and it is certain that diet 

 exercises a modifying effect (v. Koranyi). J 



Where small doses are employed, the changes are distributed 

 throughout the entire vascular system (Braun). Of the observers 

 who employed larger doses, the greater number describe changes 

 in the aorta only. The changes appear first and are most marked 

 in the upper portion of the thoracic aorta, though they are 

 occasionally met with in a slighter form in the abdominal aorta. 

 According to v. Rzentkowski, the most frequent site is at the 

 fork where the vessel branches. The macroscopic findings, as 

 described by different authors, agree in their main points with 

 those originally set forth by Josue. 



At first, small, whitish, granulated patches, of about the size 

 of a pin's head, make their appearance upon the inner surface of 

 the aorta, and gradually combine to form round or band-like 

 plaques. They early undergo calcification, patches no larger 

 than a pin's head assuming an indented cup-like form. Later on, 

 cup-like, round or oval aneurysmal pouchings are formed, often 

 with rough chalky ridges between them. Diffuse calcification is 

 also observed, though its occurrence is somewhat rare. 



The histological changes (Braun) consist, in the first instance, 



* Josue thinks that young rabbits are not susceptible to adrenalin. 

 This view is confirmed by O. Loeb and Githens, but is disputed by Ben- 

 necke. 



t Albinos and the more finely-organized breeds are less resistant to 

 adrenalin. 



t According to v. Koranyi, rabbits fed on carrots have a greater power 

 of resistance than those fed on oats. 



16 



